BIOPROSPECÇÃO DE FUNGOS CELULOLÍTICOS DO CERRADO BRASILEIRO PARA HIDRÓLISE ENZIMÁTICA DE BAGAÇO DE CANA-DE-AÇÚCAR

Abstract

Nowadays, enzymes are used to obtain many products in several areas, and new applications are constantly being developed. Mainly, the search for cellulolytic enzymes, which are able of hydrolyzing agroindustrial residues, releasing fermentable sugars, usable in different biotechnological processes, including the second-generation ethanol production. Filamentous fungi are one of the most important producers microorganisms of cellulolytic enzymes and because of this, researchers are conducting screening programs in order to isolate and identify fungi capable of producing lignocellulolytic enzymes. This study aimed the bioconversion of sugarcane bagasse into fermentable sugars using cellulolytic enzymes produced by fungi isolated from sugarcane bagasse in the Brazilian savanna. Sugarcane bagasse at Brazilian savanna from two industries was used as source of microorganisms, isolated by serial dilution and identified by sequencing genomic DNA. It resulted in 20 different fungal species. These fungi were cultured for 21 days and tested for enzymatic profile using Paper whatman nº1 (FPase) and carboxymethylcellulose (CMCase) following the protocols of Ghose (1987), Miller (1959) and Mandels & Weber (1969). The isolates, Paecilomyces parvisporus, Aspergillus fumigatus and Fusarium oxysporum showed the best results of enzyme activity compared to the others. The supernatants enzyme of the respective fungi, with loads of 10 FPU g-1 and 25 FPU g-1 were used for the enzymatic hydrolysis of sugarcane bagasse. After a period of 72h they were fermented by the yeast Saccharomyces cerevisiae YPO4. The results of enzymatic hydrolysis show that the best conversions were obtained by Paecilomyces parvisporus with enzyme load of 10 FPU g-1 to obtain 1.03 g L-1 of glucose with 24 h of hydrolysis. And by the Aspergillus fumigatus with enzyme load of 25 FPU g-1 also with 24h achieved similar results by hydrolysis of 1.02 g L-1 glucose, obtained the highter level and stabilization analysis of sugars in the 48 and 72 hour keeping up with 1.09 g L-1 glucose. Bioprospection of cellulolytic fungi from Brazilian savanna evidences the industrial potential of its microflora to produce enzymes and the use of agricultural waste such as sugar cane bagasse are allies in resolving the problematic of biofuels, contributing to the reduction of spending and mitigating environmental problems.